Telephone system



5 a 0 2 2 M A k 0 my 1 m .2 H 0 M a 2 y 1 fl .Em NS. w n RE Aw smw M mu Ff Aug; 19 1924,

Patented Aug. 19, 1924.

UNITED STATES ATENT rriaE-g FRANK s. IRVINE, or HUNTINGTON, NEW YoRK, Assrenon-ro wnsrnnn ELECTRIC 1 COMPANY, mcoaronnrrm, or new YORK, N. Y., A CORPORATION or new YORK.

TELEPHONE sYs'rn vr.

Application filed June27, 1921,. Serial Nb. 480,552.

and useful Improvements in Telephone Systerns, of which the following is a full, clear,

concise, and exact description.

This invention relates to telephonee r c I I circuit of this characterthe'firstbrush group change systems and more especially to those systems in which machine swltchingiapparatus is used in the establishment of talking connections.

In certain types of y ms where selective v a when two or more brush group's contamvciop switching devices are employed,particularly those adapted for the extension of connections in a full-automatic manner, the sub scribers lines terminate at the central oflice in the multiple banks of line finder switches. To secure the advantages incidentthereto, the subscribers lines may be divided into relatively large groups, the capacity of the finder switches being adapted to correspond with the size of the line group. The finder switches may be provided each with a plurality of brush sets, each set serving a subdivision or brush group of a major group of subscribers lines. 3

The number of equivalent finder switches necessary to serve a major group of lines depends upon the nature of the tra-fiic in such group. 'In any event, aplurality of finders are provided and each line appears in a set of multiple terminals inall finders,

Considering the subdivision, all lines in a particular brush group appear in terminals of all the finders which are accessible by the corresponding sets ofbrushes, The same is true of each of the remaining brush groups.

According to one well-known construction,

the brushes are normally in a non-contacting same time, it is necessary to preclude the possibility of a' simultaneous movement among the finders in response to the pres ence of simultaneous'calls on the subscribers lines. This is attained by utilizing a start.

ing circuit common to all brush groups of "taneous call lines for starting, in motion a single idle finder switcln The starting circuit contains a corresponding element for each group, such as a relay contact, and may be closedat any group in response to a call therein, to start an idle'switch. Once the startingfcircuit is closed at a given group 'itis renderedlun available to all other groups. M I

Owingto'the series nature of a starting:

has-a preference overall other groups, the second'brus'h, group a preference over all succeeding groups, and so on, inappropriah ing the starting circuitfor use ata time existing calls; ,This means that, as between any two groups, one hasan inherent advan tage over the other. e

The object of the presentinventionis to provide means, in a system of the character above: outlined, whereby any group of lines which has appropriated a switch for use in 7 Afeature of theinvention relates to the provision of a device individual to each.

group, which is operatedvvhenever a call is extended in. such group, and which is held operated toprevent that group from extend ing a further, call untilanlunsati'sfied simul-, 5

in every other group has been served. i r These and other features contemplated in the present invention .willfbecome moref clearly understood from the detailed description given hereinafter and from the ap pended claims. j

Referring to'the drawing Figs. 1' and 2,

taken'in order, illustratea portion of a me- Q chanical" exchange." system embodying the subject-matten'of this invention. Fig. '1

shows a portion of eachofthree successive brush groups of subscribers lines entering i r v 1 the central ,oifice together with 'certam controlelement's individual to thedifferent line's,

and, otherelements fcomnron to all the lines of abrush"groupfwhile:still other devices are illustrated common to all brush groups. Fig. 2 illustratesin' diagrammatic manner a part of each of two "groups of equivalent line v 1 finder switchesfinthe terminal banks of plurality of sets of brushes mounted on a vertically movable brush shaft, the brushes of the brush sets being designed to normally move over the terminals of the bank without engaging the same and arranged when taken for use to be tripped into contactrelation with the terminals by a trip rod common to a number of different switches. The details of the construction and operation of a switch of this'character are shown and described in the patent to J. L. McQuarrie No. 1,177,044, issued March 28, 1916.

The sequence switches such as the switch 218 shown in the drawing, one of which is to E. B. Craft and J. N. Reynolds No.

. details of the operating circuits. r

be assumed, for illustration, that the calllng, I subscribers lines such as lines 100, 120, 130,

provided for controlling the circuits of each line finder switch and its associated selector switch,.are of the well-known type such, for example, as the one described in the patent 1,123,696, issued January 5, 1915.

In order that a better understanding may be had of the purpose of the invention, a general description will first be given of the grouping arrangement of the calling subscribers lines before proceeding with the Itv may 140, etc., are dividedinto major groups of 300 lines each. Accordingly, the finder switches, in the terminal banks of which the subscribers lines appear, have a capacity for accommodating 300 lines. It may further be 3 considered that the finder switches are provided with fifteen sets of brushes, each set of brushes consequently having access to twenty different subscribers lines. In order to give adequate service to a group of 300 lines, a number of finder switches are provided to each such group. These finders are arranged in two groups, half of the finders appearing in the A group and the other half in the B group asindicated in Fig. 2. The twenty subscribers lines of each brush group appear before the corresponding brushes of all finder switches in both the A and the B, groups. Further- .more, the brush groups of subscriberslines are subdivided into two smaller groups of ten lines each. The first ten lines, known as the A subgroup, appear in the lowerhalf of the section served by the brushes of all finders in the A group of finders and appear in the upper half of, the section served by the corresponding brushes of the finders of the B group. Similarly, the second ten lines, known as the B subgroup of the brush group, appear in the upper half of the section served by the'brushes of the finders of the A group and in the lower half of the "section served by the corresponding brushes of the finders in the B group. In other words, all of the fifteen brush groups of lines are subdivided into two subgroups, the

A subgroup and the B subgroup. The A By such an arrangement the finder switches in the A group may normally serve calls appearing in the A subgroups of lines whereby these switches will only be required the brushes of the A finders.

to traverse a maximum distance corresponding to ten sets of terminals. B finders normally serve the B subgroups of lines.

Likewise, the

Whenever, a call occurs in either an A or B subgroup, a finder normally serving such group will be taken for use provided an idle finder is available at the time. If, however, all finders of the A group are busy when a call occurs in an A subgroup, or if all finders of the B group are busy when a call occurs in a B subgroup, then a finder in the other group will be taken for use, in which case, the operating finder will be required to pass over the first ten sets of terminals in each brush group before itcan make connection with the terminals of the calling line. For a more complete description of a line finder system wherein the brush groups of lines are subdivided into smaller groups and appear non-correspondingly in the terminals of two different groups of equivalent line finder switches, reference is made to the application of S. B. Williams, jr., Serial No. 348,510, filed .December 31, 1919, Patent No. 1,380,857, issued June .7, 1921, and also to applicants copending application, Serial No. 411,880, filed September 22, 1920, Patent No. 1.461528, issued July 10, 1923.

In Fig. 10f the drawing three of the fifteen brush groups of lines are illustrated. Only two lines, namely, lines 100 and 120 of the first brush group are shown. The line 100 is one of the ten lines of the A subgroup of the first brush group and its conductors 101 and 102'will be seen to appear in the terminals of the lowerhalf of thesection served by the brushes of the finders 200, 205 and 210 of the A group of finder switches. Only three finder switches of each of the A and B groups havebeen shown, there being p ent advantage over all succeeding; groups of lines in the matter of appropriating the as many provided as the nature of the, traffic warrants. p

The first brush group of terminals {of the A finder switches are divided in accordance I with the division of the brush group. of lines into two sections, the lower sectionindiw cated at 232 and the upper section indicated at 233. In a like manner, the firstb ruslr groupof terminals ofthe finders 215, 220, 225,etc., of the B group is divided into two sections, the lower section 235 andthe upper section 234. V Hence, the subscribers line 100 which is one of the ten-linesof the A subgroup of the first brush group in addition to appearing in the, lower or first choice section 232 otall finders oi the A group also appears in the terminals of the upper section' 234 of-all finders in the B group. The line 120, which is one of the lines in the Bsubgroup of the first brush group, appears as a first choice ,line in the lower section 235 of the B, finder switches and also as a second choice line-in the upper section of terminals 233 brush group of lines together with a relay Lines 130 and 140 are. respectivelylines in the A and B subgroups of the second of the A finder switches.

brush group of lines and appear in a similar fashion in the terminals of the A andB groups offinder switches served by thesecond brushsets. At the lower part of Fig. 1 the elements belonging to the third brush groupof subscribers lines are shown, Al-

though the lines for this brush group. have been omitted, it is understood that they, too, will appear before the third brush sets of the tematic arrangement is required whereby. idleswitches-may be chosen and taken for use to find the calling lines without interference. To this end a common starting mechanism consisting of relays shown in Figs. 1 and 2 is provided for all brush groups of lines and operates to start an idle line finder ine ther of the A, or. B. groups dependent upon the location of the calling line. This starting mechanism is rendered effective by the completion of a' starting circuit which extendsin series to all of the severalbrush groups. Upon the initiation of the call in any brush group, the starting cir-,

cuit is modified at a point corresponding to, that group and taken temporarily for the sole use theerof to the exclusion of all re- As soon as a finderis maining groups. i started the starting circuit is restored to its normal condition and becomes availablefor calls in the-same or other groups.

7 Due to: .the series nature of this starting circuit the first brush. group in the series has'zan inher' starting circuit at a time when a call is initiw ated in; such groupfsimultaneously with the ailadvantage o-ver allremaining groups of Si: multaneous calls, L1kew1se,= the third'brush group has a'preference over. all succeeding subservientonly to thefirst brush group, has

groups and so onto the last group in order,

I which has the leastop-portunity of all in ap- I pro-p-riating the starting circuit. WVith such I an arrangement, any group may successfully a start theline finder to serveits calling lines without delay provided no; other group coni tains aco-eznstrng call, but where two or u more linesin ditl'erent groups initiate calls slmultaneoi'isly, some onegroup thereof will always have the preference and the otherwill'be required to wait. 1 To overcome this ob ectionablefeature inherent to the simple series starting circuit, a relay such asthe,

relays 109, 137 and 143 ,is provided for each 145 common.toallgroups. j Considering the ;controls the starting circuit, as will be seen herelnatter, deenerg zes shortly, provided no other a group contains a simultaneous call,,- I

and by deene'rgizing renders the first groupv in conditionto again initiate the movement of a finder switch to serve a subsequent call-' ing line; However, if some other group containsaco-existing call, the relay 145 will be energized andrelay- 109 upon operating in v the first group will remain energized. Re-

.lay 109 thus remains lockedto prevent any other line in the first group from initiating a subsequent call unt l a call originated simultaneouslyv in each .of the remaininggroups has been satisfied.

A detailed description of the operation it will now be given. Assume at first that the subscriber of some one of the ten linesinthe A subgroup of the first brush. group, such i as the subscriber of line 100,;desires to obtain a telephone connection. jUpon IeIDOV-L ing his receiver from the switchhookthe sub} scriber completes a circuit from battery 'throughthe winding of the line relay 103, inner contact of cut-ofi relay 104k, conductor I02,,throughthesubstation loopfof line 100,

conductor 101 outer contact of relay 104 to ground. The line relay 103 operates and, closes a circuit from ground through. its left contact,-winding of group relay 105, normal"contacts at the inner right armature of said relay, conductor 14:9, innermost contact of relay l46 to battery. Relay, 105

which common to all the relays 1,03,

relay 109, conductor 148, winding of relay 145 to battery. Relay 145 energizes in this circuit. Relay 105 also establishes a circuit from ground through its left contact, conductor 115, inner right contact of relay 108, which relay is common to all lines in the brush group, inner back contact of relay 111, right contact of relay '109,"left-hand winding of relay 110, conductor 116, next to the inner contact of relay 146 to battery. The relays 111 and 110 above mentioned are also common to all twenty lines in the first brush group. Relay 110 becomes energized in the circuit traced and completes the starting circuit from ground through the outer contact of relay 108, right-hand winding of relay 110, inner right front contact of relay 110, conductors 117 and 118, winding of starting' relay 146to battery. Relay 146 operates toopen the original energizing circuit through the left-handwinding of relay 110, but relay 110 remains operated in the circuit just tracedthrough its right-hand holding winding and the winding. of relay 146. A circuit is now established from ground through the next to the outer contact of re-' lay 146, conductor 119, outer left contact of relay 110, winding of relay 111 to battery. Relay 111 operates and locksin' a circuit from battery through its winding and inner front contact and inner right contact of relay 108, conductor 115, left contact of relay 105 to ground. Relay 111 closes a circuit from ground through its outer contact, right-hand winding of relay 109 to bat- 'tery. Relay 109 at its outer left contact opens the circuit traced for relay 145 and this latter relay'becomesxdeenergized, since it is assumed that in the case under discussion no'other group of lines is making a simultaneous call.

The starting relay 146 also prepares a circuit from groundthrough the next to the outer contact, conductor '119, inner left contact of relay 110, conductor 150, outer right contact of relay 105, conductor 151,, con ductor 152, back contact of relay 201, left contact 'of relay 202, outer back contact of relay 203, lower contact of spring 2130f sequence switch 218 closed in position 1, innermostleft contact of relay 208, righthandwinding of relay 2 09 .to'battery. Since the first line finder switch 200 in the A group is assumed to be idle, sequence switch 218 individual to such line finder is in its nor-Q mal position, position '1, and hence the lower "contact of spring 213 is closed and the relay 209 is deenergized. The relay 209 operates in the circuit traced and closes a holding circuit for -itself from battery through its righthand winding, inner left contact and lefthand winding. of said relay to ground through the contact of relay 212. Relay 209 completes a circuit from ground through its outer left front contact, middle left contact 'of'relay 208, normal contact at the right armature of relay 202, winding of relay 202 to battery. Relay 202 becomes energized and locks in a circuit from battery through its winding and right front contact, conductor 243, outermost contact of relay 146 to ground. I Relay 202 at its left contact opens the circuit previously traced through the as above explained. i

Relay 209 also completes a circuit from. ground through its right contact, winding of the updrive power magnet 236 to battery.

The power magnet 236 of'the chosen line 1 9O finder 200 is energized and acts in the wellknown manner tocause the brush shaft 227 to move upwardly for the purpose of tripping the particular set of brushes which has access to that section of the terminal bank containing the terminals of the calling line.

It will be noted that the relay llO at the energization of the trip magnet 237 which controls the tripping of the brushes at each of the line finders in'both the A and the B groups having access to the first group of lines. Consequently, the magnet 23'? when energized moves the common trip rod 244 into a position such that, upon the upward movement of the brush shaft'227 of the selected switch, the brushes are tripped into operative relation with the terminals'of the bank. V I

Shortly after the brush shaft 227' has commenced its upward movement prior to the time the tripped set of brushes'encounter the terminals of the'first line, the brush 239 makes engagement temporarilywith segment 240. A circuit is thereupon momentarily established from ground through brush 239,

of current from battery through the winding of relay 146 to ground at the brush 239 is right-hand winding of relay 209, but relay 209 remains operated in the locking circuit L,

in shunt of the path previously traced through the right-hand holding winding of relay 110. Hence, relay 110'being shunted I energizing circuit for relay 211.

releases its armatures and in so doingjopens the circuit of trip magnet 237 allowing the trip rod 244 to be restored to normal so as not to cause the tripping of the corresponding sets of brushes on any other line finder switch, provided such a switch ismoved. Belay 110 also opens the circuit traced for the energization of relay 209. Furthermore, relay 110 at its inner-right contact connects the starting conductor 117 throughto the corresponding contact of the relay 139Qat the next brush group, whereby a call originating in any other brush group may cause the starting of another line finder switch. l/Vhen the brush 239 moves off the segment 240, the circuit of relay 146 is opened and since relay 110 is now deenergized the original energizing circuit of relay 146 is also,

severed and this latter relay retracts its armatures.

As soon as the brushes 222, 223, 224 and 226 engage terminals 245, 246, 247 and 248 of the calling subscribers line 100, a circuit is established from battery through the Winding of relay 212, brush 226, terminal 248, conductor 113, right contact of line relay 103, left hand winding of relay 108 to battery. It will be noted that a circuit is closed through the right hand winding of relay 108 at the time relay 111 operates. The right-hand winding of relay 108, however, is so constructed that the flux createdthereby is insutiicient to operate the relay, but will maintain the armaturesin their operated position once they have been attracted. Relay 108 now operates in the circuit traced through its left-hand winding and opens the locking circuit of relay 111. Relay 111, being slow to deenergize, requires an appreciable interval to retract its armatures.

' Relay 212 opens the circuit of relay 209, but this relay remains energized an inst-ant longer by means of a holding circuit from battery through its right-hand winding, inner left contact and left-hand winding of said relay, conductor 242, commutator 24-1, brush 239 to ground, When the'brnshes 222, 223, 224, and 226 areaccurately centered on the terminals of the calling line, the brush 239 engages an insulating segment of commutator 241. The holding circuit of relay 209 is opened and this relay deenergizes. Relay 209 at its right contact opens the circuit of theupdrive power magnet 236 causing the brush .shaft 227 to cease its upward movement. At the time the brush shaft 227 moves away from its normal position the ofi-non mal contact 217 is closed to complete an lVith relay 211 operated and relay 209 deenergized, a circuit is closed from battery through the Winding ofsequence switch magnet 218, con tact of spring 219 (1), outer contact of relay 211, outer left back contact of relay 209 to ground. The sequence switch 218 advances out ofposition 1 into its succeeding positions.

Relay 211 also closes a circuit from battery through thewinding of relay 208 to ground at the inner contact of relay 211. Relay 208 serves to indicate the line finder switch. he

lVith the sequence switch 218 in one of its advanced positions, a circuit is closed from busy condition of the relay 104 to ground. 1 The manner in which this circuit ,iscompleted for the cutoff relay is shown in the above mentioned application,

Relay; 104 operates and opens the circuit of the line relay 103 causing this relay to become deenergized. Relay 103 opens thecir cuit of the groupjrelay 105 which also rebattery over conduct-or 249, brush224, ter-' ninal-247, conductor .112, winding of cut-01f Serial No.411,880,filed September 22, 1920.

leases itsjarmat'ures provided no other line;

inthe A subgroup is calling and'has its line relay energ zed. As soon as the line relay 103 releases its armatures, 1t opens the operating circuit. through the left-hand Windo ing of relay l08. Relay 108, however, is

held energizedby means of'a circut through its righthand winding to ground at the outer contact of the ,slow-to-release relay 111. As soon as thenecessary interval has elapsed, the relay 111 retracts its armatures and opensthecircuit of relay 1 08, whereby this relay also becomes deenergized. ,Relay lll at its outer contact opens the circuit through the right-hand Winding of relay 109 and relay 109 releases its armatures due to relay 202 and the outer back contact of relay 203 now leads over the upper contact of spring ,213 (2+18), lower contact of spring 214 (1), of the sequence switch individual to the next line finder 205, provided this switch is idle at the time, conductor .250, and thence through the right-hand winding of a relay corresponding to relay 209 to battery. In this manner the second line finder 205, which is the first idle switch available at thetime, is started in operation to find the calling subscribers line;

f ConsiderneXt that the subscriber-of, line 120, whichis one of the ten lines inthe B subgroup ofthe first brush group, wishes to extendatelephoneconnection; Upon removi inghis receiver fromthe switchhook a cit:

as relays 123, 126, etc.

relay 145.

cuitis established from battery through the winding of line relay 123, inner contact of cut-oif relay 124, conductor 122, over the loop of the calling line, conductor 121, outer contact of relay 124 to ground. The line relay 123 operates and closes a circuit from ground through its left-hand contact, winding of relay 125,- the normal contact at the inner right-hand armature of said relay, conductor 149, innermost contact of relay 146 to battery. Relay 125 which, like relay 105 is common to all of the ten lines of the B subgroup, is operated in response to the energization of any of the line relays such Relay 125, upon operating, locks in a circuit from battery through its inner right contact, winding of said relay to ground at the left contact of relay 123. Relay 125 establishes a circuit "from round throu h its left contact conductor 114, outer'left contact of relay 109, conductor148,through the winding of relay 145 to battery, causing the'energization of Relay 125 also completes a circuit from ground through its left contact, conductor 115, inner contact of relay 108, inner back contact of relay 111, right contact of relay 109, left-hand winding of relay 110 and thence over conduct-or 116 as formerly traced to battery. Relay 110 becomes energized in this circuit and closes the above traced locking circuit for itself through its right-hand winding and the winding of the startingrelay 146. Relay 146 operates and opens the circuit through the left-hand winding of relay 110. Relay 110 closes a circuit for relay 111, causes the energization of the trip magnet 237 and also completes a circuit from ground through the next to the outer contact of relay 146, conductor 119, inner left contact of relay 110, conductor 154, outer right contact of relay 125, conductor 155, back contact of relay 204, left contact of relay 207, outer back contact of relay 206, conductor 251, lower contact of spring 221 of the sequence switch individual to the finder'215 of the B group, closed in position 1, provided this finder is idle, conductor 252, and thence through the winding of a relay corresponding to relay 209. The finder switch 215 is thus started in operation to hunt for and'find terminals of the calling line 120 in the B subgroup, which line appears as a first choice line in the B finder switches.

lVhen the finder switch 215 moves away from normal position, the brushes 253, 254, 255 and 256 are tripped due to the displaced condition of the common trip rod 244 and make engagement with their cooperating terminals. Also, upon the initial movement of the brush shaft, a brush similar to brush 239'encounters a segment similar to segment 240 placing a ground upon the common conductor 117 which shunts the relay 110. Re-

lay 110 deenergizes and an instant later the starting relay 146 retracts its arinatures as previously explained. From this po1nt on the operation of the finder switch to find and seize the terminals of the calling line 120 proceeds in the same manner as already explained in connection with the finder switch 200. When the line is found and the cut-off relay 124 has been operated for a sufficient interval, relay 111 becomes deenergized, permitting the. release of relays 108 and 109.

It may occur at certain times that all of the finders in either the A or B groups are simultaneously busy when a call is initichoice will be taken for use provided such groups contain an idle switch. For example, if the subscriber of line 100 initiates a call when all of the finders of the'A group which normally serve this line are busy, then one ofthe finders in the B group is appropriated for extending the line. Referring to Fig. 2 it will be observed that the circuit through the outer left contact of relay 208 extends thereafter through contacts of similar relays for other finders, and thence to ground. This particular convention means that the circuit includes the outermost left contact of a relay corresponding to relay 208 of each of the remaining finders 205, 210, etc., of the A group of switches. Hence when all of the finders are busy and all of the relays similar to relay 208 are operated, this series circuit is closed through the left-hand winding of relay 203 to battery. Relay 203 operates. Vhen under these conditions the subscriber of line 100 initiates the call and relays 110 and 146 are energized a circuitis established from ground through the next to the outer- .most contact of relay 146, conductor 119,

inner left contact'of relay 110, conductor 150, outer right contact of relay 105,'conducto'r 151, conductor 152, back contact of relay 201, left contact ofrelay 202, outer front contact of relay 203, winding of relay 204 to battery. Belay 204-operates and establishes a circuit from ground through its front contact, left contact of relay 207, outer back contact of relay 206, conductor 251, and thence to; the relay corresponding to relay 209 at the firstidle finder switch in the B group of switches. This switch is, therefore, started in operation, moves over the first group of ten terminals which it normally serves and into the second group of ten terminals to find and seize the cal].- ing subscribers line 100. A similar series of operations occur whenever a line in the B subgroup calls at the time when all finders of the B group of finders are simultaneous ly engaged andioneof the-A finderswitches istaken for. use.'. b e

To; illustrate the purpose, of the series starting circuit, the next case to'be COIlSlCle ered is-theone wherein thesubscriber of the line inthesecond briushs group extends a call atatime when no Waitingoalls existsin the first brush group. Assume that the; sub.- scriber. of line 130 Wishes? to' obtain" a telephone-connection. Oil-removing his receiver: from: the sW-it-chhook, a; circuit: similar to the one. already traced is established-i for the line relay 133, which in turn, causesthe. energi; zation: of the. group relay .1'35.-. The-group relay locks: in: an obvious circuitandestablishes a: circuit; from ground. through. the leftcontact. of relay. 135, conductor 1.56., outer left contact: of relay. 137,. whiclrlike. relay, 109: is common to the second brush group, conductor 1&8, Winding of: relay 145 to battery. Relay 135 also. 01058953H0l1'0l1lt; from ground througha its leftv contact, conductor 1'57, inner contact of. relay 136,..in ner back contact of relay 138,.rightcontact of relay 137, left hand Winding of relay1'39, thence over conductor 116 to battery. Relay 189 operates and closes a: c-ircuit from ground through the outer contact of relay 136, right hand winding: and: inner: ri ht front: contact of relay 139,-. conductor 158, inner. right back contact ofrelay 110,.WlliCl1 relay is deenergized at this time,starting conductor 117 conductor 118, Winding; of starting relay 146 to. battery. Relay 146 operates and-relay 139'remai'ns locked in this circuit. Relay 146 also; completes arcircuit from ground? through the next to the outer contact of said-relay, conductor 119, outer left contact of'relay'1-39,.Winding of relay. 1-38 to battery. Relay 138 operates andlocksin a. manner similar to thatexplainedinwcone nection With relay 111 andaalso closesa circuit fortheenergization;of relay. 1-37. Furthermore; relay 146; closest-a circuit from ground through the next to its outermost contact, conductor- 11-9, innerleftcontact. of. relay 139,-conductor'l59; outer nightcontactof relay' 185, conductor 160,.conductors 1'51 and 152-, and thence as previously traced: through the Winding! of. relay: 200 of the; finder switch 200.- Relay. 1'39nin 1 addition closes acircuit. from gr0und through 1 its outerright contact' conductor 161*, winding of trip magnet 238 to battery. Theztrip magnet 238 positions the common trip rod 257 preparatory to tripping the. set of brushes having-access to the second brush group of lines at any' finder switchflwhich ismovedupwardly; The' operation of the finder switch 200 to seize theterminals oft-he calling; line 1'30 proceeds in the; manner now Well understood.

It will be observed that when the relay 110 of the'first' brush group isoperatedadur-fl ing lillGTllltGIIVkI-l that/the) finder: switchi lSibiEi are deenergized.

ing; started to; seize a calling line; in: that group; the conductor 117 is disconnected from conductor 158: and thereby. from all sueceedingybrushg groups.attheinnorright back contacts of? said relay. This meansthat succeedingagroup Which, has: been; made simultaneously or shortly subsequent. to the' call: in the first; group oan 'receiveattention;

'l he same isltnueoffthe group relay139 which is operated during the interval: a finder, switch-i 1s being started tose1ze a call 111g: line in the-seoondibrush group. That: is

toisay-,,With relay 139enehgized-,ftl1e start 1 111g: circuit: extending; over conductors a 117. w

andi158- is disconnected from the conduotor 1.62. .and hence from allisucceeding; brush groups, whereby/calls in these groups canznot/be served until botlrrelays 110:and11:39 The same relation 5 exists izhroughout, all succeeding; brush= groups of mes, v

,Assume:- next. that two. calls: are: made simultaneously, one'of which occurs on:.any.

line in the first brush, group, 511011: as; either lines100for 'line120tanditherothen callion any, line im the second: brush group-such as line 130 or line 11 10; In response to. these calls both relays-1:10 a11d189. are energized; oven the; circuit: previously traced through; their left-hand:windings; Relay 11.05; locks in:;'t he circuittriaced through its right-hand 'WlDCL ing: and inner right front, contact; condue-' tor 117-; and'! thence through the winding. of

relay 1416f-t0 battery; VVhenrelayJJtdenengizes: in'this circuit: it opens the operating circuit. for the left-hand. Winding: of; relay 1:39. and relay 139' deenerzg-izes, since'it: can;

not: lookzt'hrough its right-hand; Winding.

dues to thefactthat'conduetor"158 is disconnested. from conductor: 117 at theinner right:

baclccOntact ofirelayllO. Hence, thercalling line. in the firstrhrnsh group will receive im+ mediate attention, While/the cal1ing;:=line= in the second% grouprmustfvvait until a finder has beenistartedi and relays 111.0 and;-14l6 have deenergizedito; complete 1 the. startingcircuit;

Immediately when these relays. become; deene ergized, relay 113,9 is again operated; in; a: cincuit. oven-its leftehandt-windingf andzthis time succeeds; in: looking] through it's right-hand:

winding and the; Winding of ,relay' 14:6, whereby another finder" SWit'ClL is started "to gr0up1..-- 1 1 1 Should" a call "have existed simultaneously,

seize; the. oallihgqlineim the; second brush:-

im the third brushgroup, it would be required tdwaituntillbothlof the. calls in: the first and second groups havebeen" taken care .o-fbeforerelay lkt could suceeed inz closing a: locking circuit for-itselfin series with the starting relay/146. I

Were some PDOVISIOIlJlOl) made, several:

. therefore,- remains operated due to the fact simultaneous calls in the first brush group would receive attention in preference toany call in a succeeding group which may have beeninitiated'at the same time'; For as soon as relay 110-had deenergizedafter starting a finder to find one or the calling lines in the 'first brush group, it would immediately re'-' energize due to the existence of another call in such brush group thereby preventing the corresponding relay ofany succeeding group 145, conductor 148., outer left contact of relay 137, conductor 156 to ground at the left contact of relay 135. Consequently,the energization of relay 109, while it opens one of the branches of the circuitfor operating the relay 145, is without efiect upon this relay, since another of the branches of the operating circuit of said relay is-closed at the left contact of relay 135 due to the fact that a line in-the second brush group is calling. WVhen, after the calling line in the first brush gro-uphas been found,relay 111 deenergizes,it opens theoperating circuit through the right-hand winding of relay 109'. Relay 109, however, cannot release its armatures due tothe circuit closed from battery through the left-hand winding and inner left contact ofsaid relay, conductor 147, contact of relay 145 to ground. Relay 109,

that relay 145 is 'sti ll'energized which indicates that a call in some other brush group is awaiting attention; r

j Should there be oneor more other calling --lines in the first brush group, relay 105 or relay 125 is operated as the case may be, but the relay 110 cannot again be energized since the operating circuit through its left-hand winding is held open at the right contact of relay 109. With the relay 110 deenergized thestarting circuit is extended through to the second brush groupand relay 139 is now operated and looks. through itsjright-hand winding over conductor 158 and conductor 117, and thence through the winding of the starting relay 146. A finder is'thereupon started to extend the callingline 130 in the second brush group.

" s soon as relay 139 locks in series with relay 146, relay 138 is operated and causes the energization of relay 137. Relay 137 opensthe' branch of the circuit which held a plurality the common relay 145 energized and relay 145 becomes deenerglzed provided that no line 111 any other succeeding group is calling at this time. Immediately that relay 145're-;

tracts its armature itopens the holding cir-' cuit of relay 139 and this relay becomes de energized to permit other calls which may be existing in the first brush group to causethe energization' of relay 110 to start-line finders. If, however, a call is simultaneously existing-in Some other brush group at the time relay 137 becomes operated, relay 145 is still held energized over a branch of its op-' erating circuit closed at such other group.

By means of this arrangement no brush group of lines, regardless of the inherent advantage it may have over other brush groups, can succeed in establishing more than one connection until a call is satisfied in every other group having simultaneous calls therein.

In case one or more lines in every brush group is making a simultaneous call, the relav 145' operates over parallel branches lock to the contact of relay 145. The relay 145 remains energized to prevent the 'de" energization of relays 109,137,143, etc.,'after they have once operated, to prevent another call from being extended in their respective groups until a call has been served in each and every other group having a calling line therein. At this time the last parallel branch for holding therelay 145 is opened and this latter relay releases to, in turn, open the holding circuits of all relays 109, 137, 143. call in the'fil'st group, provided there exists one, may be'made and so on in the same manner as before.

What is claimed is:

1. In a telephone system,

on any of said lines for operatingone of said switches to extend such line, means op'- erative when a swltch is being taken for use to extend-said first line for rendering said second line ineffective to operate a switch provided a call exists on said third line, and means for rendering said second line effective to cause the operation of a' switch as soon as the switch taken for use by said thirdline commences to operate;

2. In a telephone system, a number of groups of lines, one of said groups includ ing a first line and a' second line,'another of said groups including a third line,

of finder switches serving said lines,{1n':ans responsive to the initiation of a call on any'of said lines for lVith these relays all released, a

a number or groups of lines, one ofsald groups including moving one of said switches to extendsuch line, means operative whenia switch being taken for use to extend said first line for rendering said second line ineffective to operate a switchprovided a call exists on said third line, means effective as soon as the switch taken for use by said first line has commenced to operate for rending said third line efiective to operate one of said switches, and means for rendering said second line effective to cause the operation of a switch as soon as the switch taken for use said third line commences to operate.

3. In a telephone system, a plurality of groups of lines, a plurality of automatic] switch serving said lines, means responsive to the initiation of a call on any of saidlines for moving one of said switches to "extend such line, means operative when (a; switch is being. taken for use to extend a line in any particular group for rendering the remaining lines in such group inefiectivs to move one of said switches provided a call exists on a line in any other group, and means for rendering a second line in said particular group effective to cause the operation of a switch as soon as the switch taken for use by the calling line in said other group commences to operate.

4. In a telephone system, a plurality of groups of lines, a? plurality of automatic switches s rving said lines, means responsive to the initiation of a call on any of said lines for moving one of said switches to extend such line, and means operated. when a switch is being moved to extend a line in any particular group, if some other group contains a simultaneously calling line, for.

rendering the remaining lines in said par-- ticular group inefi'ective to move one of said switches until said simultaneously calling line has been extended.

5. In a telephone system, a plurality of groups of lines, a plurality of automatic switches serving said lines, means responsive I to the initiation of a call on any of said lines for moving one of said switches to extend such line, and means operated when a switch is being moved to extend a line in any particular group, if other groups con tain simultaneously calling lines, for renden ing the remaining lines in said particulargroup inefi'ective to move one of said switches until all the simultaneously calling lines in said other groups have been extended.

6. In a telephone system, a plurality of groups of lines, a plurality of automatic switches for extending said lines, means responsive to the initiation of a call on a line in any particular group for moving one of said switches to extend such line, means for rendering a second simultaneously calling line in said particular group ineffective to move one of said switches until the switch respondingto said first line has started in motion, and means operated when a switch is being moved to extend a line in saidparticular group for rendering the remaining lines in such group ineffective until alnyline in, any other group which may be calling simultaneously has caused the movement of a switch for extending the same;

7. In a telephone system, a plurality of groups of lines, a plurality? of automaticsw'itche's for serving said lines, means vfor initiating a 'number oi calls in each of said groups simultaneously, means for operatin said switchesto extend a calling line in sac-1 of said "groups successively, means when a calling line-in the lastfgroup has been extended for operating switches to extend a remaining callin line in each of said groups successively in the same order, and means for rendering a second calling'line in any group ineiiective to operate a switch until a simultaneously calling line in each of all other groups has been extended.

8, Ina telephone system, a plurality of groups of lines, a plurality of automatic switches for extending said lines, means responsive to the initiation of a call on any one oi'said lines for moving one of said switches to extend such line, a plurality of relays individual respectively to said groups, means when a, line in any particular group nntlates a call to move one of said switches for operating the relay individual to such particular group, and means re-l sponsive to calling lines in other groups for switches for extending said lines, means re-' sponsive to the initiation of a call on any one of said lines for moving one of said switches to extendisuch line, a plurality of relays individual respectively to groups, a common relay for all groups,

, said means when a line in any particular group initiates a call tomove one of said switches for operating the relay individual to. such ,v particular group, means responsive to call ing lines in other groups for operating said common relay, and means controlled by the common relay for maintaining operated the relay individual tofsaid particular group to render the reinalningjlines 1n such particular group ine'fiieotive to move one of said switches until said calling lines in other groups have'been extended,

said lines for starting one of said switches in motion to find and extend such line, and means operated when a'finder switch is being' takenfor use to extend a line in any each having a plurality of brush sets, each brush set serving .a group of said lines, means responsive to the initiation of a call on any line'in any group'for selecting the proper brush set of an idle' finder switch and for starting such switch in motion to find the calling line, and means operated at the time a switch is taken for use to extend a line in any particular group for rendering the remaining lines in said group temporarily ineffective to start another idle switch provided a call exists on a line' in some'other group.

12. In. a telephone system, a plurality of groups of lines a plurality of automatic switches for serving said lines, means for initiating a plurality of simultaneous calls one on a line in each group, means for op-' erating said switches to extend the calling lines successively in a certain order and means when any group contains a second simultaneously calling line for rendering such second line ineffective to operate a switch for extending the same until a simultaneously calling line in each of all other groups has been extended.

In witness whereof I hereunto subscribe my name.

FRANK s. IRVINE. 

